1. Field of the Invention
This invention relates to the stabilization of hydrides and other compositions in which deuterium and/or tritium may be substituted to derivatize the hydride composition and produce a highly stabilized deutero- and/or tritiato-species. In a particular aspect, the invention relates to reagents useful as metal source compositions for ion implantation, chemical vapor deposition, laser or light-induced deposition, plasma-induced or ion beam-induced deposition, or other metal formation processes, in which the metal source compositions have been stabilized by the incorporation of deuterium and/or tritium substituents therein.
2. Description of the Related Art
In the fabrication of advanced semiconductor devices, processes such as III-V MOCVD and p/n doping by ion implantation ideally require the use of Group III and Group V hydrides.
However, the hydrides of the heavier elements of Group III and Group V are unstable or in some cases are simply not known. For instance, stibine is only stable at very low temperatures (-78.degree. C.), decomposing spontaneously at room temperature, while indane cannot be isolated.
In addition, alkyl or aryl metal hydrides such as HSbR.sub.2 and H.sub.2 SbR, wherein R is alkyl, are also unstable.
Although literature reports indicate that researchers have synthesized and used metal hydrides as precursors when stored at low temperatures, widespread commercialization has not been possible due to the limited stability of the hydrides to light, heat and metal surfaces (i.e., stainless steel).
Sophisticated microelectronic components and device heterostructures are driving the development of CVD precursors that exhibit useful volatility and the ability to deposit high-purity films. Currently, many III-V devices based upon strained layer superlattices and multiple quantum wells (MQW) are fabricated by molecular beam epitaxy (MBE). MBE is relatively slow and expensive when compared to alternate thin-film growth techniques used for microelectronics.
Although chemical vapor deposition (CVD) offers a low-cost, high throughput approach to device manufacturing, a lack of suitable, low temperature CVD precursors has hindered its widespread applicability. This is particularly true for Sb-based heterostructures that display important optoelectronic and electronic properties, including InSb, InGaSb, InAsSb, GaAlSb and InSbBi. Volatile and thermally stable Sb precursors would facilitate the chemical vapor deposition of antimonide thin-films, as required for the large scale, controlled production of antimonide based lasers, detectors and microelectronic sensors.
Antimonide materials are attractive for commercial infrared optoelectronic applications. The compositional variety and stoichiometry of III-V compound semiconductors allows for nearly complete coverage of the infrared spectrum. Bandgaps ranging from 2.5 eV in AlP to 0.2 eV in InSb can be achieved by forming strained thin-films with the proper elemental and stoichiometric compositions. Materials of greatest interest include InSbBi and Inas-SbBi.sub.8 for long wavelength (8-12 mm) infrared detectors, InAsSb and InGaSb1.degree. for mid-infrared absorbers in military applications, and InSb/In.sub.1-x Al.sub.x Sb.sub.11 light emitting diodes (LEDs) for mid-infrared chemical sensor applications. Many of these materials, however, as mentioned above are metastable compositions that necessitate high-purity films and low processing temperatures.
Antimonides are also of great interest as semiconductor infrared lasers. For instance, a type-II quantum well superlattice laser, comprised of InAsSb active layer with alternating InPSb and AlAsSb cladding layers, provides 3.5 mm emission upon electron injection. Similarly, mid-infrared lasers comprised of InAs/InGaSb/InAs active regions with lattice-matching to AlSb cladding layers were also demonstrated. The device fabrication requires thin-film processing of elemental aluminum, antimony, gallium and indium to produce both the active and cladding layers, and thereby, presents a significant technological challenge. The inherent physical properties of Ga, Sb and In necessitate low processing temperatures to alleviate inter-diffusion, melting, and re-evaporation (i.e., InSb melts at 525.degree. C.). Unfortunately, current Sb CVD sources, such as trimethyl antimony, require processing temperatures in excess of 460.degree. C. to achieve precursor decomposition and useful film growth rates.